Increasingly, audio records of crimes and military events such as friendly fire deaths are used in forensic analysis. Emergency (911) calls from the victim's or eyewitness's cell phone, police radio transmissions, or military radio communications provide a record of the event that validates or refutes the subjective recollections of the individuals involved. Furthermore, the actual audio from the event can make compelling courtroom evidence.
Such use of portable radio communications is hampered by the typically poor quality of the audio signal, and in particular by the audio record's limitation to the radio holder's voice, which, by design, and particularly in emergency situations when the radio holder is speaking loudly and rapidly, dominates the signal and masks other speakers and background sounds at the crime scene.